Single Phase Induction Motors - torque characteristics of a universal motor both for D.C. and A.C. supply
1 Answer
A universal motor is a type of electric motor that is designed to operate on both alternating current (AC) and direct current (DC) power sources. It is commonly used in applications where the motor needs to be versatile and work with different types of power supplies. These motors are often found in appliances such as vacuum cleaners, power tools, and kitchen appliances like blenders.
Torque characteristics of a universal motor for DC and AC supply can be summarized as follows:
1. Direct Current (DC) Supply:
When a universal motor is operated on a DC power supply, the torque-speed characteristics are similar to those of a typical DC series motor. The torque produced by the motor is directly proportional to the square of the armature current, and the speed of the motor decreases as the load torque increases.
Torque-Speed Relationship: The torque produced by the universal motor is given by the equation: T ∝ Ia^2, where "T" is the torque and "Ia" is the armature current. This means that torque is directly proportional to the square of the armature current.
Speed Regulation: Universal motors have relatively poor speed regulation under DC supply. As the load on the motor increases, the speed decreases significantly. This is due to the high armature current and magnetic saturation effects.
2. Alternating Current (AC) Supply:
When operated on an AC power supply, the torque-speed characteristics of a universal motor are influenced by the interaction of both the stator and rotor magnetic fields.
Torque-Speed Relationship: The torque produced by the universal motor under AC supply is given by the equation: T ∝ V^2/R, where "T" is the torque, "V" is the applied voltage, and "R" is the total circuit resistance. Unlike the DC case, the torque is proportional to the square of the applied voltage divided by the resistance.
Speed Regulation: Universal motors also have poor speed regulation under AC supply. However, the speed drop is not as severe as in the DC case. The speed decrease is due to factors such as the frequency of the AC supply, the inductive reactance of the windings, and other losses.
It's important to note that universal motors exhibit higher starting torque and better speed control under DC supply compared to AC supply. However, they are more commonly used on AC power due to the convenience of using a single power source in many applications.
Keep in mind that the actual torque-speed characteristics can vary based on the specific design of the universal motor, the quality of the materials used, and the operating conditions.
Torque characteristics of a universal motor for DC and AC supply can be summarized as follows:
1. Direct Current (DC) Supply:
When a universal motor is operated on a DC power supply, the torque-speed characteristics are similar to those of a typical DC series motor. The torque produced by the motor is directly proportional to the square of the armature current, and the speed of the motor decreases as the load torque increases.
Torque-Speed Relationship: The torque produced by the universal motor is given by the equation: T ∝ Ia^2, where "T" is the torque and "Ia" is the armature current. This means that torque is directly proportional to the square of the armature current.
Speed Regulation: Universal motors have relatively poor speed regulation under DC supply. As the load on the motor increases, the speed decreases significantly. This is due to the high armature current and magnetic saturation effects.
2. Alternating Current (AC) Supply:
When operated on an AC power supply, the torque-speed characteristics of a universal motor are influenced by the interaction of both the stator and rotor magnetic fields.
Torque-Speed Relationship: The torque produced by the universal motor under AC supply is given by the equation: T ∝ V^2/R, where "T" is the torque, "V" is the applied voltage, and "R" is the total circuit resistance. Unlike the DC case, the torque is proportional to the square of the applied voltage divided by the resistance.
Speed Regulation: Universal motors also have poor speed regulation under AC supply. However, the speed drop is not as severe as in the DC case. The speed decrease is due to factors such as the frequency of the AC supply, the inductive reactance of the windings, and other losses.
It's important to note that universal motors exhibit higher starting torque and better speed control under DC supply compared to AC supply. However, they are more commonly used on AC power due to the convenience of using a single power source in many applications.
Keep in mind that the actual torque-speed characteristics can vary based on the specific design of the universal motor, the quality of the materials used, and the operating conditions.